Hormonal requirement and tissue specific expression of several molecular forms of beta-1-4 galtransferase is being investigated. In mammary gland its expression is modulated by lactogenic hormones and is also dependent on the functional differentiation of the mammary tissue. The primary goal of this project is to identify cell lines which: a) do not produce 1-4 galtransferase, b) produce very low levels, and c) very high levels of the enzyme. Such cell lines will be used for transfection experiments to determine the structure- function relationship of galtransferase and alphalactalbumin, and also the hormonal regulation of expression of the enzyme. In the present study we are: A) screening several cell lines for 1) the activity of 1-4 galtransferase, 2) the molecular form of the protein produced, 3) mRNA levels for the enzyme, and 4) mRNA size class produced; B) investigating the effect of steroidal and mitogenic hormones and their combinations on any of the parameters stated in A); C) determining cell-cycle dependent expression of the enzyme in Swiss mouse 3T3 cells.